1. Field of the Invention
The present invention relates to a yarn take-up machine for taking up at a high speed a yarn coming from a spinning beam and, more particularly, to a take-up machine having an elevating frame designed to be subject to reduced vibration at the time of resonance.
2. Related Art Statement
A yarn take-up machine is primarily composed of a turret disc which turns around a horizontal shaft in relation to a machine frame; two bobbin holders projectingly installed from the turret disc; an elevating frame which is guided along a column in the machine frame and vertically moves upwards and downwards; a touch roller supported on the elevating frame; and a traverse device supported on the elevating frame. That is, the bobbin holders are projectingly installed on the machine frame indirectly through the turret disc.
In the conventional yarn take-up machine described above, the speed of the bobbin holders during the taking-up operation from the start of winding to the end of winding changes within a wide range. The touch roller for applying a proper contact pressure to the packages P wound on the bobbins B mounted on the bobbin holders will be affected by this change in the take-up speed. That is, the bobbin holders will become a source of vibration, causing the elevating frame holding the touch roller to resonate. In conventional take-up machines, the elevating frame is designed so that the natural frequency of the elevating frame will become less than the rotational vibration frequency of the bobbin holders.
In recent years-what has been sought is a yarn take-up machine which can be operated within a wide speed range from a low speed to a high speed; however, with this increase in the speed range, the rotational vibration frequency of the bobbin holders also tends to increase. For example, in a wide range of taking-up speed the rotational vibration frequency of the bobbin holders ranges from minimum 24 Hz to maximum 290 Hz. There is, therefore, such a problem that it is practically difficult to design the elevating frame having no natural frequency to operate at such a wide range of rotational vibration frequency, and there exists a limit to the use of a high-speed spun yarn take-up machine.